1. Field of the Invention
The present invention relates to a method of manufacturing an anode for a solid oxide fuel cell.
2. Description of the Prior Art
Recently, considerable attention has been focused on the fuel cell as an energy source, not only from the viewpoint of conservation of resources, but also that of the effect on the environment. The solid electrolyte type of fuel cell in principle has a high electric generating efficiency because of the high operating temperatures of 800.degree. to 1000.degree. C. in the fuel cell, and because the materials of construction are all solid it has the advantage of ease in handling, so that progress is being made in the practical application of this device. FIG. 1 shows a rough outline of the structure of a solid electrolyte fuel cell wherein the center is a solid electrolyte 1, on one surface of which a fuel electrode 2 (hereinafter referred to as "anode") , and on the other surface an air electrode 3 (hereinafter referred to as "cathode") are formed. The anode 2 and the cathode 3 form a pair of interfaces 4 and 5 respectively with the solid electrolyte, and are connected by an external circuit through a load 6. When a fuel gas such as hydrogen (H.sub.2), methane (CH.sub.4), or the like is supplied to the anode 2, and an oxidizing agent such as air, oxygen (02), or the like is supplied to the cathode 3, an electromotive force is produced between the anode 2 and the cathode 3, and a current flows through the load 6 connected to the external circuit. The following types of reactions occur at the interfaces 4 and 5 of the anode 2 and the cathode 3 respectively.
Interface 4: O.sup.2- +H.sub.2 .fwdarw.H.sub.2 O=2e- PA0 Interface 5: O.sub.2 +2e-.fwdarw.O.sup.2-
In this type of solid oxide fuel cell it is known that the microstructure of the electrodes has a major influence on the cell performance. The effect of the microstructure of the anode 2 is particularly great. Normally a cermet is used for the anode 2, and the technology for obtaining the optimum microstructure is extremely important.
A method for preparing the anode 2 is commonly known wherein generally an Ni-YSZ (yttria stabilized zirconia) cermet or the like, Ni particles or NiO particles, and YSZ particles are mechanically blended, coated onto an electrolyte layer, and annealed. Problems occur with this technology because the Ni particles or NiO particles and YSZ particles are mechanically blended so that the dispersion of the Ni particles or NiO particles is poor. When the electrode is annealed or when generating electricity the Ni particles tend to cohere, with the result that the performance of the anode, drops, and the adhesion of the anode to the electrolyte layer is poor. In addition, there is a tendency toward a large contact resistance and peeling of the electrode, so that the life span is shortened.